End brush with male projection

ABSTRACT

An end brush for use in a dental unit or the like includes a base formed of solified fiber material. The base includes an outwardly projecting portion, which is adapted to be received within a mounting structure provided on the dental unit. An apparatus and method for forming the end brush are disclosed.

This is a division of application Ser. No. 07/402,341, filed Aug. 31,1989, now U.S. Pat. No. 5,072,482.

BACKGROUND AND SUMMARY

This invention relates to an end brush formed of a bundle ofthermoplastic fibers, in which one end of the bundle of fibers is formedof solidified fiber material. This type of brush is useful in anapparatus for cleaning the teeth, wherein rotation is imparted to thebrush.

It is known to form an end brush from a bundle of thermoplastic fibersin which an end of the fiber bundle is subjected to a heating step so asto melt the fiber ends, and to thereafter cool the melted fiber materialso as to provide a substantially rigid base to the end brush.

Application Ser. No. 07/283,089, filed Dec. 12, 1988 discloses an endbrush of this type, and also an apparatus for manufacture thereof. Inthe noted application, the resultant end brush has a base formed ofsolidified fiber material, and a passage formed in the base. The passagehas splined walls formed by insertion of a heated male splined pin intothe fiber ends. The heated pin melts the fibers as it is inserted intothe fiber bundle. After the heated pin is withdrawn from the fiberbundle and the melted fiber material has cooled, the melted fibermaterial forms a substantially rigid base for the end brush. The brushis then placed onto a dental unit which includes a rotating driveshafthaving a splined configuration similar to that of the passage formed inthe base of the end brush, for imparting rotation thereto. An apparatuswith which such a brush is useful is disclosed in U.S. Pat. No.4,827,552 issued May 9, 1989.

While the end brush as described above has proven satisfactory inconstruction and operation, it has been found that cost savings andquality enhancements are attainable over the known brush and apparatus.The present invention is directed to this end.

In accordance with the invention, a brush assembly, such as for use in adental unit, comprises a brush formed of a bundle of fibers extendingfrom a base. The base is formed of solidified fiber material andincludes an outwardly extending dimensionally defined projection. Drivemeans is provided for imparting rotation to the brush, and mountingmeans is associated with the drive means for securing the brush thereto.The mounting means includes a recess adapted to receive the outwardlyextending projection of the base of the brush. Means is provided forsecuring the outwardly extending projection of the base of the brushwithin the recess. The projection is formed of solidified fibermaterial, and preferably includes a transversely enlarged portion. Thesecuring means comprises an area associated with the recess forreceiving the transversely enlarged portion, so that the brush providesa snap-fit onto the mounting means by a push-on force mating theprojection with the recess.

With this construction, the driveshaft in the known tooth cleaningapparatus can be eliminated, and is replaced by mating of the projectionwith the recess provided in the mounting means. The recess ispreferrably formed in an outwardly facing surface of a gear, which isadapted to be rotatably driven by the dental unit drive system, forimparting rotation to the brush. In a preferred embodiment, positiveengagement means is provided for preventing slippage of the brushrelative to the gear during operation. The positive engagement means mayinclude a rib formed on the base of the brush protruding laterally fromthe projection and, means associated with a wall of the recess forengaging the protrusion so as to prevent slippage.

The invention also contemplates an end brush constructed substantiallyin accordance with the above description.

Also contemplated by the invention is a method of forming an end brush.The method includes providing a bundle of generally parallel fibersformed of thermoplastic material, and liquifying the the fiber ends atan end of the bundle so as to unite the fibers. The liquified fibermaterial is formed to a shape providing an outer portion lying in afirst plane substantially perpendicular to the fibers, and an innerportion extending below the outer portion so as to form a projection.The liquified fiber material is then solidified, so as to form a rigidbase. In a preferred embodiment, the fiber ends are liquified by movinga heated element into engagement with the fiber ends so as to melt thefibers. Thereafter, the melted fiber material is cooled so as tosolidify the material and form the base. The liquified fiber material isformed by providing the heated element with an upper outer surface andin inner surface disposed therebelow. Movement of the heated elementinto contact with the fiber ends melts the fiber material adjacent thefiber ends so that the melted fiber material conforms to the shape ofthe heated element. The melted fiber material adjacent the upper outersurface forms the outer portion, and the melted fiber material adjacentthe inner surface forms the inner portion projecting below the outerportion. In a preferred embodiment, the heated element comprises anouter sleeve with a movable insert. Upward movement of the pin after themelted fiber material as solidified knocks the brush off of the heatedelement, preparing the heated element for subsequent usage in forminganother brush.

The invention finally contemplates an apparatus for forming an end brushfrom a bundle of thermoplastic fibers. The apparatus comprises means forreceiving the bundle of fibers and selectively clamping the bundleadjacent an end thereof. A movable element is movable into contact withthe end of the fiber bundle. Heating means is provided for heating themovable element prior to contact with the fiber ends, so that the fiberends are liquidified when the movable element is brought into contacttherewith. The movable element is provided with means for forming theliquified fiber material to a shape providing an outer portion lying ina first plane substantially perpendicular to the fibers, and an innerportion extending below the outer portion so as to form a projection.The apparatus includes cooling means for solidifying the melted fibermaterial so as to form a rigid base. As described previously, themovable element preferably comprises a tubular sleeve, with an insert orpin disposed within the sleeve. The upper end of the pin is disposedbelow the upper end of the sleeve when the movable element is moved intocontact with the fiber ends. The forming means thus comprises the upperend of the sleeve providing the outer portion, and the cavity formed byupper end of the pin and the inner wall of the sleeve providing theinner portion. The inner wall of the sleeve is preferably provided witha circumferential groove or indentation disposed above the upper end ofthe pin. In this manner, when the movable element is brought intocontact with the fiber ends, melted fiber material flows into theindentation to provide an area of enlarged transverse dimension to theprojecting portion of the brush base.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate the best mode presently contemplated of carryingout the invention.

In the drawings:

FIG. 1 is an elevation view of an apparatus for manufacturing an endbrush according to the invention;

FIG. 2 is an enlarged partial elevation view, in section, showing thecomponents of the apparatus of FIG. 1 for forming the male projection onthe base portion of the end brush;

FIG. 3 is a view similar to FIG. 2, showing a prior art apparatus forforming an end brush in which a substantially central passage isprovided in the base of the brush;

FIG. 4 is a cross sectional view of an end brush as manufacturedaccording to the invention;

FIG. 5 is a view of a prior art removable head tooth cleaning apparatuswith which an end brush made according to the invention is useable;

FIG. 6 is a cross sectional view similar to FIG. 4, showing a brush madeaccording to the prior art apparatus as shown in FIG. 3;

FIG. 7 is a view of the prior art brush of FIG. 6 as installed on adental unit, which includes a driveshaft for mating with the passageformed in the base of the end brush;

FIG. 8 is a sectional view taken generally along line 8--8 of FIG. 7;

FIG. 9 is a view similar to FIG. 7, showing an end brush according tothe invention as installed on a dental unit, including means forreceiving the male projection formed on the base of the end brush;

FIG. 10 is a partial sectional view taken generally along line 10--10 ofFIG. 9;

FIG. 11 is an enlarged partial elevation view of a portion of FIG. 9,showing a positive engagement system between the base portion of the endbrush and the gear in which it is mounted; and

FIG. 12 is a partial sectional view taken generally along line 12--12 ofFIG. 11.

DETAILED DESCRIPTION

With reference to FIG. 1, an apparatus for manufacturing an end brush isdisclosed, substantially similar in construction to that as disclosed inapplication Ser. No. 07/283,089 filed Dec. 12, 1988, now U.S. Pat. No.4,884,849, the disclosure of which is hereby incorporated by reference.While the apparatus of FIG. 1 is well described in the noted patent, abrief description of the apparatus will be undertaken.

A fiber bundle 20 is fed through an adjustable aperture 22 formed in anaperture plate 24. Aperture plate 24 consists of a stationary end 26 anda movable end 28, with a fluid-operated cylinder 30 interconnected withmovable end 28 via a connecting rod 32. Stationary end 26 is held inplace by means of a z-bracket 34 and bolts 36, 38. Pressurized fluid isselectively supplied to either the rod end or the piston end of cylinder30, for selectively moving movable end 28 leftward or rightward, asdesired. Upon full rightward movement of movable end 28, fiber bundle 20is clamped within aperture 22 between movable end 28 and stationary end26. When movable end 28 is moved leftwardly, the clamping force onbundle 20 is released, thereby allowing bundle 20 to be moved throughaperture 22.

A reciprocable cutoff knife 40 is located below aperature plate 24.Knife 40 is interconnected with a fluid operated cylinder 42 via aconnecting rod 44. Knife 40 is movable leftwardly and rightwardly uponthe selective supply of fluid pressure to either the rod end or thepiston end of cylinder 42.

A knock-off hammer 46 is located slightly below cutoff knife 40, and isinterconnected with a fluid operated cylinder 48 via a connecting rod50. Upon selective supply of fluid pressure to either the rod end or thepiston end of cylinder 48, hammer 34 is reciprocably movable in a backand forth direction.

In accordance with the present invention, an outer sleeve 52 isconnected at its lower end to a stop collar 54. An insert, or pin, 56extends through the passage of sleeve 52. A collar 58 is formed on pin56, and is disposed within a cavity 60 formed in stop collar 54. Thelower end of pin 56 is provided with a flanged base 62, located within ahousing 64. A spring 66 is provided between base 62 and the lowersurface of housing 64, for biasing pin 56 upwardly. Housing 64 isinterconnected with a fluid operated cylinder 68 via a connecting rod70. Upon selective provision of pressurized fluid to either the rod endor the piston end of cylinder 68, housing 64 is reciprocably movable inan up-down direction.

The upper end of pin 56, shown at 72, is normally disposed below theupper end of sleeve 52, shown at 74. As will be explained, pin 56 ismovable relative to sleeve 52 during operation.

An induction heating coil 76 circumferentially surrounds the upperportion of pin 56.

At approximately the same elevation as heating coil 76, a cold airnozzle 78 interconnected with a cold air supply 80 is provided.

Upper stationary stops 82 are positioned above stop collar 54. A lowerstop plate 84 is positioned below stop caller 54, and is interconnectedwith a fluid operated cylinder 86 via a connecting rod 88. Uponselective provision of fluid pressure to either the rod end or thepiston end of cylinder 86, lower stop 84 is reciprocably movable in aback and forth direction.

Referring to FIG. 2, the relationship of sleeve upper end 74 and pinupper surface 72 is illustrated. As shown, a circumferential groove 90is formed in the inner wall of sleeve 52. Groove 90 is located above pinupper surface 72, and is spaced below sleeve upper end 74.

In operation, the above-described apparatus functions as follows.Movable end 28 of aperture plate 24 is moved leftwardly so as to openaperture 22. The leading end of fiber bundle 20 is fed through aperature22 until it is flush with the bottom surface of aperature plate 24.Movable end 28 of aperture plate 24 is then moved rightward to itsclosed position, so as to clamp fiber bundle 20 into aperture 22.Induction heating coil 76 is then actuated, so as to heat the upperportion of sleeve 52, as well as the upper end of pin 56. Fluid pressureis then supplied to the piston side of cylinder 68, so as to extend rod70 and move housing 64 and collar 54 upwardly until the upper surface ofcollar 54 contacts the lower surface of upper stops 82. This actionforces upper end 74 of sleeve 52 into the fiber ends, which are melteddue to the high temperature of sleeve 52 produced by heating ofinduction coil 76. The liquified fiber material conforms to theconfiguration of the upper portion of sleeve 52, as shown in FIG. 2, andflows downwardly into the passage in sleeve 52 into contact with upperend 72 of pin 56. The melted fiber material flows into circumferentialgroove 90. After full upward movement of the sleeve and pin assembly,and sufficient time has passed so as to allow the melted fiber materialto conform to the configuration of the upper end of the sleeve and pinassembly, a cold air blast from cold air nozzle 78 is then directed ontothe upper portion of sleeve 52. This acts to cool sleeve 52 and therebysolidify the melted fiber material. Movable end 28 of aperature plate 24is then opened, and fluid pressure supplied to the rod side of cylinder68 so as to move the sleeve and pin assembly downwardly, thus drawingfiber bundle 20 through aperture 22 in aperture plate 24. After fiberbundle 20 is drawn down a predetermined distance, fluid pressure issupplied to cylinder 42 so as to actuate cutoff knife 44, severing fiberbundle 20 a predetermined distance above the fused fiber ends. Thesleeve and pin assembly is then drawn down further while stop collar 54is held stationary by lower stop 84, so as to move, and pin 56 upwardlywithin sleeve 52 to eject the formed brush from the upper end of sleeve52. Knock off hammer 46 is then actuated for removing the formed brushfrom the apparatus, whereafter sleeve 52 is then moved upwardly inpreparation for another cycle.

While the above-described apparatus and method have been formedsatisfactorily, it is comtemplated that various changes may be made inorder to effect a more efficient, higher-production operation.

With reference to FIG. 4, a brush 92 made according to theabove-described and apparatus and process is illustrated. Brush 92includes a plurality of fibers 94 extending outwardly from a base formedof solidified fiber material. Fibers 94 are preferably such as sold byE. I. duPond deNemours under its trademark "Tyvex". As shown, the baseincludes an outer portion 96 lying in a plane substantiallyperpendicular to fibers 94. A substantially cylindrical inner portion 98extends below outer portion 96. Inner portion 98 results from the meltedbristle material conforming to the configuration of the upper end of thesleeve and pin assembly as shown in FIG. 2. Inner portion 98 includes asubstantially flat end portion 100 and a sidewall portion 102. A lateralprotrusion 104 is provided on sidewall portion 102, resulting frommelted bristle material flowing into circumferential groove 90 formed inthe inner wall of sleeve 52. Protrusion 104 is located toward the lowerend of sidewall 102.

As is seen, outwardly extending fibers 94 are intergrally attached attheir lower ends to the solidified base, due to the melting of fibermaterial which forms the base. The fibers extend through the interior ofcylindrical inner portion 98, for connection to cylindrical portion endwall 100.

Referring to FIG. 3, the prior sleeve and pin assembly for forming theend brush as illustrated. Like reference characters will be used tofacilitate clarity. A splined projection 104 is formed at the upper endof pin 56. The sleeve and pin assembly is maintained in its FIG. 3position and moved upwardly into the end of the fiber bundle, afterheating of the upper portion of the sleeve and pin assembly. Projection104 is forced into the fibers, and the fiber ends are melted so as toform a base corresponding the shape of the upper end of the sleeve andpin assembly.

A brush made according to this method is shown in FIG. 6, and includes asplined axial passage 106 formed by splined projection 104 afterwithdrawal from the fiber bundle and cooling of the melted fibermaterial. As shown in FIG. 7, splined passage 106 is adapted to matewith a male splined driveshaft 108 projecting outwardly from a crowngear 110 rotatably mounted within the end portion 112 of a brush head.Upon rotation of crown gear 110 by means of rotation of a drive gear114, rotation is imparted to drive shaft 108, and positive engagement ofdriveshaft 108 with the spline in the wall of passage 106 impartsrotation to the brush.

FIG. 8 illustrates the configuration of the splines on driveshaft 108,and on the walls of passage 106.

Referring to FIG. 5, end brush 92 constructed according to theconvention is adapted for use in a tooth cleaning instrument comprisinga hand-held power unit 116 and a removable head portion 118. Power unit116 and head 118 are preferrably such as manufactured by Better HealthConcepts, Inc. of Wauwatosa, Wis. under its trademark "Proclean 2000".Referring to FIGS. 5 and 7, the drive configuration illustrated in FIG.7 is a prior art drive system, and FIG. 5 is modified to accept brush 92as manufactured in accordance with the present invention. Such a systemis disclosed in FIG. 9, and reference is made thereto for a detailedexplanation of the interrelationship of brush 92 with removable head118.

Head 118 includes an end housing 120 provided with a hollow interior 122opening outwardly through a passage 124 in part defined by acircumferential lip 126. A crown gear 128 is rotably mounted withinhollow interior 122 of end housing 120. A rear thrust collar 130 isplaced within a recessed area formed in end housing 120, and the rearend of crown gear 128 is received within rear thrust collar 130. Aforward thrust collar 132 is placed in a forward recess formed in hollowinterior 122, and receives the neck 134 of crown gear 128. Crown gear128 includes an outwardly facing forward surface 136.

An outwardly facing recess is formed in forward surface 136 of crowngear 128, and is adapted to accept the cylindrical inner portion 98 ofthe base of brush 92. The recess formed in crown gear 128 includes anouter restricted portion 138 and an inner expanded portion 140.

Brush 92 is adapted to be snap-fit into the recess formed in forwardsurface 136 of crown gear 128. The snap-fit is accomplished by forcingcircumferential protrusion 104 formed at the base of brush 92 throughthe recess restricted portion 138 until protrusion 104 snaps into recessexpanded portion 140. The depth of recess restricted portion 138 issubstantiably equal to, or slightly greater than, the portion ofsidewall 102 in the base of brush 92 between the uppermost surface ofprotrusion 104 and the lowermost surface of outer base portion 96. Inthis manner, a secure engagement of protrusion 104 with the shoulderformed between recess expanded portion 140 and restricted portion 138 isensured. The lower surface of base outer portion 96 contacts the area ofcrown gear forward surface 136 adjacent the recess formed therein.

The resiliency provided to the cylindrical projection 98 formed at thebase of brush 92 accommodates repeated removal and reconnection of brush92 to crown gear 128, as often as desired by the user.

Circumferential lip 126 provides lateral support for the outwardlyextending fibers of brush 92, preventing flaring of the fiber materialduring use.

As can be seen, the provision of cylindrical projection 98 mating withthe recess formed in crown gear outer surface 136 eliminates the needfor driveshaft 108 to secure brush 92 to crown gear 128, as was requiredin the prior art embodiment shown in FIG. 7. This elimination ofdriveshaft 108 substantially reduces the cost of manufacture ofremovable head 118, both due to elimination of the component part aswell as the labor involved in installing the part. In a typical packageoffered for sale, two of the removable heads such as 118 are provided tothe customer. The construction as shown in FIG. 9 thus becomes even morecost reductive.

In addition, certain benefits are offered by the design of brush 92 overthe prior art brush as shown in FIGS. 6 and 7. Referring to FIG. 4, itis seen that the overall height of brush 92 is less than the prior artbrush. In the prior art brush, the central bristles, which perform themajority of the work on the tooth surfaces during operation, are of alength extending above the upper surface of the solidified end wall ofpassage 106. This length of such fibers is the critical length, in thata certain amount of stiffness is desired in order to adequately performthe work desired. If the length of the fibers above the upper end wallof passage 106 is too long, the fibers will be too floppy. On the otherhand, if the length of the fibers is too short, the fibers will be toostiff and abrasive action on the teeth and gums will result.Accordingly, the length as shown in FIG. 6 is appropriate. The samelength of the central fibers can be achieved with the design of brush 92as shown in FIG. 4 with a substantial overall reduction in the length ofthe brush. This is because the length of the central fibers, due to thepresence cylindrical projecting portion 98 on the base of brush 92,extends throughout substantially the entire height of the brush, and isnot limited by the central passage as was the case with the prior artbrush of FIG. 6. This reduction in the overall length of the brush issignificant, in that a person's mouth presents only a certain amount ofworking room between the outer tooth surfaces and the inner surface ofthe cheek. This is especially significant in the case of younger users,whose mouths are necessarily smaller and contain even less clearanceroom than does an adult's mouth, without compromising the degree ofstiffness of the brush.

With reference to FIGS. 11 and 12, a positive engagement system ispreferably provided between cylindrical projecting portion 98 of thebase of brush 92 and the portion of crown gear 128 forming the recesswithin which projecting portion 128 is received. As shown in FIG. 11, anintegrally molded rib 142 extends between protrusion 104 and the lowersurface of base outer portion 96. Rib 142 is simultaneously formed withthe base of brush 92 of solified bristle material, by slightly modifyingthe sleeve and pin assembly of FIG. 2.

Referring to FIG. 12, crown gear 128 is modified so as to provide spacedinwardly extending lobes 144, 146 and 148. Lobes 144-148 form restrictedportion 138 of the recess in crown gear outer surface 136, so as toprovide a 3-point contact with the outer surface of sidewall 102 ofcylindrical projection 98. Protrusion 104 formed on cylindricalprojecting portion 98 is again adapted for a snap-fit into expandedportion 140 of the recess in crown gear 128, past lobes 144-148. Uponrotation of crown gear 128 during operation, rib 142 is moved intocontact with one of lobes 144-148, which contact thereafter preventsfurther rotation of brush 92 due to engagement of rib 142 with the lobe.In this manner, slippage between brush 92 and crown gear 128 isprevented.

Various alternatives and embodiments are contemplated as being withinthe scope of the following claims particularly pointing out anddistinctly claiming the subject matter regarded as the invention.

I claim:
 1. A brush assembly comprising:a plurality of generallyparallel fibers bundled to form a brush having first and second ends; abase formed at said first bundle end by solidifying said fibers, saidfibers extending away from said base and terminating in said second end,the base having a first portion disposed in a plane substantiallyperpendicular to the fibers and a projecting portion extending from saidfirst portion in a direction opposite to said fibers, said projectingportion being of smaller diameter than said first portion, and havingmeans for connecting the base to a drive means for rotating the brush,the projecting portion having a protrusion extending perpendicular tothe projecting portion, for connecting the base to a drive means forrotating the brush, the protrusion spaced away from and substantiallyparallel to the first portion of the base; drive means for impartingrotation to said brush; and mounting means associated with said drivemeans for securing said brush thereto, said mounting means including arecess adapted to receive the projecting portion and means for securingthe projecting portion within said recess.
 2. The brush assembly ofclaim 1, wherein the said securing means comprises an area associatedwith said recess for receiving said protrusion so that said brush isadapted to snap fit onto said mounting means by a push-on force matingsaid projection with said recess and forcing said protrusion into saidarea associated with said recess for receiving said protrusion.
 3. Thebrush assembly of claim 2, wherein the lower surface of said firstportion of said base provides a lower shoulder, and wherein the snap fitof said projection within said recess causes engagement of said lowershoulder with an upper surface of said mounting means adjacent saidrecess, so that the movement of said protrusion into the area associatedwith said recess for receiving said protrusion causes pressure to beexerted on said lower shoulder to secure said brush to said mountingmeans.
 4. The brush assembly of claim 2, wherein said protrusion extendsabout substantially the entire periphery of the projecting portion. 5.The brush assembly of claim 1, wherein said drive means includes arotatably driven gear, and wherein said mounting means is associatedwith said gear so that said brush is mountable to said gear.
 6. Thebrush assembly of claim 5, wherein said rotably driven gear comprises agear mounted within a housing and having at least a portion exposed, andwherein said recess is formed in said gear and faces outwardly foraccommodating removal and replacement of said brush.
 7. The brushassembly of claim 1, further comprising positive engagement meansinterposed between said brush and said mounting means for preventingslippage of said brush within said recess during operation of said drivemeans.
 8. The brush assembly of claim 7, wherein said positiveengagement means comprises a rib extending between said protrusion andthe lower surface of said first portion, and means associated with awall of said recess for engaging said rib to prevent slippage of saidbrush.
 9. The brush assembly of claim 8, wherein said recess includesone or more inwardly extending lobes adapted to receive said rib forpreventing slippage of said brush.
 10. The brush assembly of claim 1wherein the projecting portion is substantiality cylindrical, theprojecting portion having a side wall and an end wall formed ofsolidified fiber material, the fibers extending upwardly from the endwall of said projecting portion and being partially contained within theside wall ofthe substantially cylindrical projection.
 11. A brushassembly comprising:a plurality of generally parallel fibers bundled toform a brush having first and second ends; a base formed at said firstbundle end by solidifying said fibers, said fibers extending away fromsaid base and terminating in said second end, the base having a firstportion disposed in a plane substantially perpendicular to the fibersand a projecting portion extending from said first portion in adirection opposite to said fibers, said projecting portion being ofsmaller diameter than said first portion, and having means forconnecting the base to a drive means for rotating the brush, theconnecting means being a rib extending outwardly from the projectingportion, between the projecting portion and a lower surface of the firstportion; drive means for imparting rotation to said brush; and mountingmeans associated with said drive means for securing said brush thereto,said mounting means including a recess adapted to receive the projectingportion and means for securing the projecting portion within said recessby engaging said rib.
 12. The brush assembly of claim 11 wherein theprojecting portion is substantiality cylindrical, the projecting portionhaving a side wall and an end wall formed of solidified fiber material,the fibers extending upwardly from the end wall of said projectingportion and being partially contained within the side wall of thesubstantially cylindrical projection.